US3138298A

US3138298A - Powder feed and metering device for flame spray guns

Info

Publication number: US3138298A
Application number: US125267A
Authority: US
Inventors: Walter A Siebein; Anthony J Rotolico; Greengrass Floyd
Original assignee: Metco Inc
Current assignee: Metco Inc
Priority date: 1961-07-19
Filing date: 1961-07-19
Publication date: 1964-06-23
Anticipated expiration: 1981-06-23
Also published as: GB946522A

Description

June 23, 1964 w $|EBE|N T 3,138,298

POWDER FEED AND METERING DEVICE FOR FLAME SPRAY GUNS Filed July 19, 1961 2 Sheets-Sheet 1 a 9 M1 vs I --2/ 6 I4 I57 l6 Q -5/ C W INVENTORS WALTER A. S/EBE/N ANT HON Y J ROTOL/CO FLOYD GREEN GRASS T'TORNEYS June 23, 1964 w. A. SIEBEIN ETAL 3,138,298

POWDER FEED AND METERING DEVICE FOR FLAME SPRAY GUNS Filed July 19, 1961 2 Sheets-Sheet 2 INVENTORS WALTER ,4. S/E'BE/N ANTHONY J. ROTOL/CO F LOVD GREENGEASS BY fiw b xg y i ATTORN United States Patent 3,138,293 POWDER FEED AND METERING DEVHIE FOR FLAME SPRAY GUNS Walter A. Siehein, Smithtown, Anthony J. Rotolico, Lynbrook, and Floyd Greengrass, Deer Park, N.Y., assignors to Metco lino, Westbury, N.Y., a corporation of New Jersey Filed July 19, 1961, Ser. No. 125,267 3 Claims. (Cl. 222-139) This invention relates to a powder feed and metering device for flame spray guns.

In flame spray guns heat-fusible material, as for example a heat-fusible metal or ceramic, is passed into a heating zone Where the same is heated to at least heatsoftened condition and propelled, as for example, onto the surface to be coated. The heat in the heating zone is generally provided by a combustion flame and in newer devices may be formed from a plasma flame generated by passing a plasma-forming gas in contact with a constricted electric arc.

In flame spray guns of the powder type, the heat-fusible material is fed into the heating zone, as for example, the combustion flame or plasma flame, in the form of a powder as for example having a particle size below about 80 and preferably below about 140 US. Standard Screen size.

The powder is generally fed into the combustion or plasma flame by gravity flow or entrained in a carrier gas which is injected into the flame.

In order to obtain high quality coatings of a given type and for a given purpose, it is necessary to accurately control the rate of powder feed into the flame and to maintain the same constant for given spray conditions.

The accurate metering and uniform and consistent control of the powder feed to the gun has presented difficulties as the rate, ease, and uniformity of powder flow, as for example by gravity through a given conduit will vary widely depending on the size, shape, and type of the individual particles and various ambient and physical conditions which, as a practical matter, cannot be accurately controlled during operation. Furthermore, even two different batches of powder which are commercially considered identical may flow differently under identical conditions.

One object of this invention is a device which allows the accurate metering and feed of heat-fusible powder, such as metal or ceramic powder, to a flame spray gun.

This and still further objects will become apparent from the following description read in conjunction with the drawings in which:

FIG. 1 is a front elevation partially in vertical section of an embodiment of a powder feed and metering device in accordance with the invention;

FIG. 2 is a side elevation, partially in section of the device shown in FIG. 1;

FIG. 3 is a cross section of a portion of the device shown in FIG. 2; and

FIG. 4 is a plan view partially in section of the plunger of the device of FIGS. 1 and 2.

The powder feed and metering device in accordance with the invention utilizes a gravity powder feed from a supply leading into a positive feed mechanical conveyor driven by a variable speed drive which, in turn, feeds into a conveying gas stream leading to the flame spray gun.

Referring to the embodiment showing in the drawing, 1 represents a housing, as for example constructed of metal or the like and provided with the horizontal cylindrical bore 2 in which is inserted the cylinder liner 3 forming a cylinder having a substantially horizontal axis. The cylinder is enclosed at its rear end by the back plate 4 of the cylinder liner 3 and enclosed at its front end by means of the removable cover 5. The cover 5 is provided with the bearing sleeve 6 and may be snapped in and out of place by means of the spring loaded plungers 7 and 8 engaging the annular shoulder 9 (FIG. 3). Rotatably positioned in the cylinder is the metering gear 10. As may best be seen from FIG. 3, the metering gear 10 is seated on the bushing 11, which, in turn, is threaded on and rotates with the shaft 12. The bushing 11 is provided with a disc 13 and the gear 10 is sandwiched between this disc 13 and a rear disc 14 which is screwconnected to the disc 13 by means of the screws 15. The discs 13 and 14 are provided with the O-ring seals 16 which move in sealing contact with the cylinder liner 3. The entire unit consisting of the shaft 12, the gear 10, the bushing 11, the discs 13 and 14, rotates with the seals 16 in contact with the cylinder liner 3 while the cylinder liner is secured against rotation by means of the set screws 17 and 18. The shaft 12 is provided with the cross pin 19 at its rear end and supported by the bearing 6 and a bearing formed by the back plate 4 of the cylinder liner 3. The cross pin 19 engages in a slot 20 in the drive coupling 21 which is secured to the end of the drive shaft 22' which rotates in the

bearings

23 and 24 and which is provided with the seal 25. The shaft 22 is rotated by means of the worm gear drive 26, 27. The shaft of the worm gear 27 is driven by means of the gear 28 which, in turn, is driven by the gear 29, secured to the shaft 30 of the motor 31. The motor 31 is a DC. electrical motor of conventional construction with a speed that can be varied, as for example, by means of the control box diagrammatically shown as 32. The motor 31 is preferably a direct current, field-controlled DC. motor using a- Thyratron control in which the back is used to govern the motor speed.

It is, of course, understood that in place of the motor 31 and drive train, as shown, any other known or conventional drive means whose speed may be controlled may be used for rotating the metering gear 10.

A gravity flow passage 33 leads through the cylinder wall and cylinder liner in communication with the teeth of the metering gear 10. The upper end of the gravity flow passage 33 is provided with the funnel-shaped bushing 34.

Mounted on top of the housing 1 on each side of the gravity flow passage 33 are the posts 35 and the clips 36. The clips 36 are screwed directly to the housing by means of a screw 37 extending through the center of the posts 35 and are attached to the cup-shaped inserts 38, secured to the clips, by means of the bowed spring washers 39. Due to this arrangement the clips may be flexed upwardly and downwardly a limited extent in a spring-like manner.

A hopper arrangement for powder is mounted above the housing. The hopper arrangement consists of the hopper container proper 40 and the base unit 41 which is provided with an automatic shut-off valve arrangement. The base unit 41 is provided with the central gravity flow discharge opening 42 extending through the bushing 43 and rubber tube 44 in communication with the gravity feed passage 33. A breather passage 45 extends through the base unit in communication with the ambient atmosphere. This breather passage is provided with the porous plug 46 which allows the passage of gas but not powder therethrough. This porous plug may, for example, be made of sintered metal. The base unit 41 is also provided with the lateral bore 47 in which is positioned the axially slidable plunger 48. The plunger, as may best be seen from FIG. 4, is provided with the rod shaped end 49 and the two connecting pins 50 which extend on either side of the tube 44 and are connected with the clampmember 51. The clamp member 51 is spring-loaded by means of the springs 52. When the rod-shaped end 49 is free, the springs 52 will axially move the plunger so that the clamp member 51 will squeeze the tube 44 shut against the pin 53, so that the plunger with the tube 44 forms an automatic closure valve. The spring 52 is retained in place by means of the screw plug 54. The base unit is provided with the slots 55 and its bottom portion extending past these slots at right angles thereto is smaller in diameter than the distance between the tips of the clips 36. By rotating the hopper arrangement 90 degrees, the clips 36 will be disengaged from the slots 55 and the unit may be lifted oil from the housing. In this position, the plunger is free to move under the influence of the spring so that the tube 44 is pinched shut and the hopper automatically closed. To reposition the hopper in place, the same is inserted in the same manner as for its removal and then rotated 90 degrees. The rotation causes the engagement of the clips 36 in the slots 55 and as the end 49 of the plunger engages a post 35, the plunger is axially moved by the pressure contact with the post compressing spring 52 and releasing the tube 44. A small indent or opening 56 is provided on the inner wall of the post 35 in which the end from the plunger 49 engages when the hopper is in position. This acts as a detent and the correct positioning of the hopper may be noted by the feel and by a click. The hopper proper 40 is screwfitted into the base unit by means of the threads 57. These threads correspond in pitch and size to the threads for a cap on a commercial can for flame spray powder so that it is possible in place of the hopper 40, to screw the base unit directly on to a powder can in place of its top. In this manner, by providing several base units on diflerent powder cans, the type of powder that is being fed through the device may be very quickly and conveniently changed by merely snapping the entire powder can with the base unit from the device and replacing it in an equally simple manner by a different powder can with a different but identically constructed base unit.

A gas flow passage 58 extends horizontally through the housing below the cylinder 2. A coupling 59 for a gas line is screwed into this passage at 61 and is provided with a jet opening 60 directed into the passage. A further coupling 62 for a gas flow line is connected to the opposite side of the gas flow passage 58 by means of the threads 63. The coupling 62 is provided with an inlet passage 64 which is slightly conically tapered. A vertical flow passage 65 communicates the lower end of the interior of the cylinder liner 3 with the portion of the gas flow passage 58 between the jet 60 and inlet 64. A vibrator, such as an electrical vibrator of conventional construction 66, may be secured into the bottom of the housing.

In operation, a gas line or a carrier gas as is conventionally in a flame spray gun is connected to the coupling 59. In connection with a flame spray gun utilizing a combustion flame, the gas may be one of the components of the combustible mixture fed to the gun, as for example, oxygen, acetylene, hydrogen, or the like. In connection with a plasma flame spray gun, the carrier gas may be the gas used as a plasma-forming gas or any other gas, as for example inert gas, etc. A flexible conduit, such as a hose, is connected between the coupling 62 and the powder feed inlet of a flame spray gun as for example the inlet for powder leading through the gun nozzle as described in copending application Serial No. 126,827, filed July 14, 1961.

The powdered heat-fusible material to be sprayed, as for example powdered metal or ceramic material, is positioned in the hopper 40 or in place of the hopper 40 a can of the powder is directly screwed to the base unit 41. With the base unit removed from the device, the plunger 49 and particularly the clamp 51 thereof will squeeze tube 44 shut tight against the pin 53 so that the discharge opening through the container is automatically sealed. The container is positioned by positioning the discharge opening in the plate 67 in the bottom of the base unit in alignment with the opening 33 so that the indented portion in this base plate 67 mates with the bushing 34. The container with the base unit is then rotated 90 degrees and secured in place by the clips 36 engaging in the slots 55. The valve is automatically opened as the end 49 of the plunger engages post sliding the plunger axially to the position shown in FIG. 1 until the end engages in the opening 56.

The powder will, therefore, flow, by gravity, through the opening 42 and tube 44 into the gravity flow passage 33 and into the cylinder between the teeth of the metering gear 10 which are positioned adjacent the gravity flow passage 33. The metering gear 10 is driven in the direction of the arrow by means of the motor 31 and the gear train as described. As the gear 10 rotates, it causes the positive feed of controlled quantities of powder between its teeth to the passage 65 dumping the powder into this passage where it flows into the gas flow passage 58. The carrier gas passes through the fitting 59 and jet openings 60, picks up and entrains this powder, carrying the same through the opening 64, fitting 62, and conduit to the flame spray gun. The gravity flow passages should be large enough so that the flow rate therethrough under any conditions should be at least as large as the maximum conveying rate of the mechanical conveyor, i.e. the gear 10. The vibrator 66, if operated, will ensure that no bridging or jamming of the powder occurs and will ensure even gravity flow thereof. Relief air to prevent the build-up of a vacuum in the container should the same be sealed at its upper end is provided through the passage and plug 46. The amount of powder fed into the gas stream may be very accurately controlled and adjusted to the gas stream by control of the speed of rotation of the gear 10, as for example, by means of the control 32. The amount of powder fed into the gas stream may thus be extremely accurately controlled independent of the gas stream flow rate and at an optimum value to a given flow rate and for given spray conditions.

The metering gear may be very simply removed for cleaning or replacement, etc. by pulling the cap 5 from the device and unscrewing the unit containing the metering gear from the shaft 12. The cylinder liner can also be replaced by simply backing off the set screws 17, 18 and sliding the liner out. When reinserted, the proper alignment of the holes is ensured by a fit of the set screws 17 and 18 in their proper recesses.

While the invention has been described in detail with reference to the specific embodiments shown, various changes and modifications which fall within the spirit of the invention will become apparent to the skilled artisan. The invention is, therefore, only intended to be limited by the appended claims or their equivalents wherein we have endeavored to claim all inherent novelty.

We claim:

1. A powder feed and metering device for a flame spray gun comprising means defining a gravity flow passage for powder, a container for powder detachably mounted above said gravity flow passage and having a discharge opening in communication with said gravity flow passage, a closure valve for said discharge opening eomprising a flexible discharge tube forming a portion of said discharge opening, a plunger, spring means normally biasing said plunger against said tube clamping said tube shut, means for automatically opening said closure valve upon attachment of said container above said gravity flow passage and for automatically closing said closure valve upon detaching said container comprising means adjacent said gravity flow passage for pressing said plunger to release said tube when said container is attached, means defining a gas flow passage, a jet opening directed into said gas flow passage, means for passing a carrier gas for a flame spray gun through said jet opening, mechanical conveyor means for positive feed of controlled quantities of powder from said gravity flow passage to said gas flow passage adjacent the outlet of said jet opening, and variable speed drive means for driving said mechanical conveyor means at a controlled rate.

2. A powder feed and metering device for a flame spray gun comprising a housing defining an enclosed cylinder with its axis extending substantially horizontally, a gear rotatably positioned in said cylinder with its teeth closely adjacent the cylinder wall, a gravity flow passage extending into the upper portion of said cylinder, a gas flow passage leading into a powder conduit for a flame spray gun, a passage from the lower portion of said cylinder leading into said gas flow passage, means for passing a carrier gas through said gas flow passage, and variable speed drive means for rotating said gear, a base unit for a powder container detachably mounted above said housing and having a discharge opening in communication with said gravity flow passage, a portion of said discharge opening being defined by a flexible discharge tube, plunger means positioned adjacent said tube, spring means normally biasing said plunger to clamp said tube shut and means mounted on said housing for engaging said plunger when said base unit is mounted thereon to force said plunger in a direction releasing said tube.

3. Powder feed and metering device according to claim 2 including a breather passage extending through said base unit communicating the interior of a powder container mounted thereon with the ambient atmosphere, said breather passage containing a porous plug.

References Cited in the file of this patent UNITED STATES PATENTS 2,011,133 Yoss Aug. 13, 1935 2,152,632 Cassiere Apr. 4, 1939 2,618,410 Merow Nov. 18, 1952 2,820,670 Charlop et a1. Jan. 21, 1958 2,953,282 Peterson Sept. 20, 1960

Claims

1. A POWDER FEED AND METERING DEVICE FOR A FLAME SPRAY GUN COMPRISING MEANS DEFINING A GRAVITY FLOW PASSAGE FOR POWDER, A CONTAINER FOR POWDER DETACHABLY MOUNTED ABOVE SAID GRAVITY FLOW PASSAGE AND HAVING A DISCHARGE OPENING IN COMMUNICATION WITH SAID GRAVITY FLOW PASSAGE, A CLOSURE VALVE FOR SAID DISCHARGE OPENING COMPRISING A FLEXIBLE DISCHARGE TUBE FORMING A PORTION OF SAID DISCHARGE OPENING, A PLUNGER, SPRING MEANS NORMALLY BIASING SAID PLUNGER AGAINST SAID TUBE CLAMPING SAID TUBE SHUT, MEANS FOR AUTOMATICALLY OPENING SAID CLOSURE VALVE UPON ATTACHMENT OF SAID CONTAINER ABOVE SAID GRAVITY FLOW PASSAGE AND FOR AUTOMATICALY CLOSING SAID CLOSURE VALVE UPON DETACHING SAID CONTAINER COMPRISING MEANS ADJACENT SAID GRAVITY FLOW PASSAGE FOR PRESSING SAID PLUNGER TO RE-